1. Field of the Invention
The present invention relates to optical communication systems and, particularly to an electronic interface for small form factor high-speed optical transceivers with high sensitivity optical receivers.
2. Discussion of Related Art
There is currently a demand for high-speed, long-distance, cost-effective, and highly integrated optical transceiver systems. Therefore, optical receiver systems that are high performance, low cost, and are of small size are desired. A transceiver typically includes both a transmitter system and a receiver system. A fiber optical transceiver, therefore, can include a receiver optical sub assembly (ROSA), a transmitter optical sub assembly (TOSA), and an electronic interface connecting the ROSA and TOSA.
For short reach and medium distance transmission, the ROSA may include a PIN photo detector based receiver for detecting light from an optical fiber. For long reach transceivers (e.g., for transmission over tens of kilometers), however, high sensitivity receivers are required to compensate for the optical signal loss due to long optical fibers. In long distance systems, then, an avalanche photodiode (APD) can be utilized instead of a PIN photodiode because of its higher sensitivity and lower noise characteristics.
The TOSA can include a laser diode and optics for coupling optical signals generated by the laser diode into a fiber. The electronic interface to the TOSA and ROSA, then, includes drivers for the TOSA, receivers for the ROSA, and power supplies to power the laser diodes and the receiver chips of the ROSA and TOSA. In conventional systems, the electronic circuitry of the power supplies, the transmission circuitry, and the receiver circuitry are well separated in order to minimize the amount of noise generated on the received signals and on the transmitted signals due to the electronics. However, such an arrangement can require a great deal of space for the transceiver system.
Therefore, there is a need for optical transceiver systems, and in particular for long reach optical transceiver systems that have a small form factor and that are arranged to minimize interference and noise on the received signals.